1. Field of the Invention
The present invention relates generally to an internal combustion engine, which includes a fuel controller formed with a fuel injection pump and fuel injection nozzles, etc. More particularly, the invention relates to a fuel injection controller, which controls the amount of fuel to be injected from the fuel injectors into the internal combustion engine, detects and controls fuel injection timing and which determines irregular condition of the controller.
2. Description of the Related Art
In general, internal combustion engines having injection devices, as for example, diesel engines and high pressure gasoline injection type engines are well known. With such engines, the precise amount of fuel to be injected and the timing of the fuel injection with respect to the position of the engine's pistons are crucial facets in, the control of the fuel injection system, and most generally are designed to comply with specific target values. Consequently, it is extremely important to know the exact time for initiating fuel injection and for determining the precise amount of fuel to be injected at that time.
For example, with fuel injection pumps in an electronically controlled diesel engines, fuel in a high pressure chamber is delivered to fuel injection nozzles by the lift of a plunger, and then is injected into each one of the cylinders in the diesel engine. Spill rings and spill valves, etc, disposed in the fuel injection pump are controlled by a driving actuator, such that the amount of fuel injected into the engine at any time satisfies a target fuel amount set according to the engine's running condition at any given time. A high pressure chamber in the plunger communicates to a fuel chamber, in such a way that a part of the fuel in the high pressure chamber is spilled into the fuel chamber. From this it is apparent that the timing of the termination of the pressurized fuel delivery from the pump to the nozzles, and thereby to each of the engine's cylinders is a crucial concern.
However, the control characteristics of these types of fuel injection pumps inevitably suffer from the deformation and wearing out of the pump's mechanical parts in addition to changes in the physical characteristics of the fuel. For example, when the cam mechanism responsible for reciprocating the pump plunger is worn down or worn out, the amount of lift of the plunger travels would decrease thereby causing the amount of fuel injected through the injector nozzle to exceed the target fuel injection amount. Further compounding, this problem would be the resultant decrease in the urging force of this pump plunger return spring. A decrease of the spring force, due to a worn cam mechanism, would cause a decrease in the injector nozzle's opening valve pressure, this in turn would result again in an increase in the amount of fuel supplied to the injector nozzle. Another characteristic problem is due to changes in the physical characteristics of the fuel due to fuel temperature increases. Consequently, the amount of fuel injected through the nozzles as well as the timing of the fuel injection and fuel injection timing may be controllably changed.
Several technologies have attempted to overcome the above-described drawbacks. Japanese Unexamined Patent Publication No. 57-32021 discloses a fuel injection device that detects the amount of fuel injected into an engine, the described device maintains control over that fuel supply amount for a period longer than had similar technology. While remaining markedly uneffected by deteriorating fuel injection pump component parts. More particularly, a pressure sensor detects the internal pressure in the plunger barrel. Based on the pear valve of internal pressure detected the fuel injection device computes the actual amount of fuel to be injected. The position of the spill valve is controlled in such a way that the actual fuel injection amount converges to a target fuel value.
Japanese Unexamined Patent Publication No. 57-62935 discloses a fuel injection timing controller for use in a diesel engine. In this controller, a single sensor detects a change in fuel pressure when pressurized fuel is spilled from injection the pump to the injection nozzles. The controller controls the fuel injection timing by using a signal detecting an increase in the periodicity of high fuel pressure conditions as a feedback signal to the controller.
Unfortunately neither of the above described devices could maintain an accurate enough correspondence between the detected data and actual fuel injector conditions. The valve detected by the pressure sensor of both devices for the internal pressure of the fuel injector pump inconsistently reflected actual changes in the amount of fuel injected by the fuel injectors. Likewise both devices failed to maintain an accurate correspondence between the periodicity of changes in the fuel injector pump pressure with that of actual fuel injector timing. However, in the above-described technologies, as the peak value of the internal pressure in the plunger which was detected by the pressure sensor, and the signal indicating the increase period of the fuel pressure are referred, the changes in the actual fuel injection amount and actual fuel injection timing do not always reflect on those detected data. In order to accurately compute the actual fuel injection amount and actual fuel injection timing, the timing (i.e., fuel injection initiating timing) when the fuel injection through the nozzles is initiated should be accurately detected.
The present invention is proposed to overcome the above-described drawbacks. In other words, in the increase stage of the fuel pressure, the present invention is accomplished while the first turning point of the increase rate is considered as the fuel injection initiating timing.